In the 3GPP specification TS 23.401 (v8.1.0) a procedure “E-UTRAN Tracking Area Update” (chapter 5.3.3.2) is defined (E-UTRAN—Evolved Universal Terrestrial Radio Access Network). This procedure defines how context is requested and exchanged between different 3GPP core network nodes (SGSN—Serving GPRS Support Node and MME—Mobility Management Entity).
In some operational situations the MME requests context from two other core network nodes (old SGSN and old MME) in the same procedure. To be able to perform this “context request” from one MME to the two other core network nodes (old SGSN and old MME), the terminal (UE) transfers these address information to the MME requesting the context from the two other nodes (old SGSN and old MME). For this procedure, and in the operational situation where context needs to be requested from two nodes, the context in the old SGSN contains latest updated bearer information and the old MME contains security information (authentication vectors), related to the E-UTRAN radio access.
The authentication vectors in the old MME and the authentication vectors in old SGSN are dedicated for use in E-UTRAN access respective GERAN/UTRAN (GERAN—GSM EDGE Radio Access Network and UTRAN—UMTS Terrestrial Radio Access Network). Due to security restrictions the GERAN/UTRAN authentication vectors can not be used by E-UTRAN. The signalling flow for this context request procedure (from TS 23.401, v8.1.0) is shown in FIG. 1.
The 3GPP specification also defines a procedure “E-UTRAN to GERAN Routing Area Update” (chapter 5.3.3.5). This procedure also defines how context is requested and exchanged between the core network nodes (old SGSN and old MME). The former procedure is performed when the UE moves from a GERAN/UTRAN access to E-UTRAN access, while the latter procedure is performed when the UE moves from an E-UTRAN access to a GERAN/UTRAN access. In the latter the SGSN instead (since the UE has moved to GERAN/UTRAN) request context information from two other core network (old MME and old SGSN) in the same procedure.
In some operational situations in the latter 3GPP procedure, the SGSN requests context from two other core network nodes (old SGSN and old MME) in the same procedure. To be able to perform this “context request” from one SGSN to the two other core network nodes (old SGSN and old MME), the terminal (UE) transfers these address information to the SGSN requesting the context from the two other nodes (old SGSN and old MME). For this procedure, and in the operational situation where context needs to be requested from two nodes, the context in the old SGSN contains latest updated bearer information and the old MME contains security information (authentication vectors), related to the E-UTRAN radio access.
The main problem with these solutions for context handling is that the signalling load increases, which influences the capacity.